According to the prior art, electric memory devices typically use semiconductor memories such as a DRAM, an SRAM, a mask ROM, a PROM including an EPROM, and an EEPROM which are based on MOS technology. In addition, a non-volatile memory such as an FRAM has been also developed recently. Semiconductor memories with more capacity and which operate at higher speed with less power consumption have been required. A processing technique which facilitates realizing a finer memory capacitor (memory cell) has also been investigated. Corresponding to these technical trends, the fine-processing technique has progressed year by year and is rapidly approaching its physical limit.
On the other hand, magnetic materials are used for the major large capacity recording media. Magnetic recording has a problem in obtaining a recording media suitable for higher recording densities and a problem that the magnetic recording relies on mechanical parts including a read-write head.
The semiconductor memories described above based on a MOS structure and a PN junction structure are not reliably used at high temperatures or in cosmic space because of their poor heat resistance and radiation resistance. Magnetic recording cannot retain highly reliable volatility at high temperatures or in the strong magnetic field environment because the magnetic recording is based on magnetization.
In the semiconductor memories and the magnetic memories, thermal and electromagnetic influence directly cause malfunctions, because the semiconductor memories and the magnetic memories relate electric state change and electromagnetic state change with a memory function (state transition). From the stand point of non-volatility, it is important to relate the memory function with a semi-permanent state change. In view of this, chemical change of material, which occurs by bonding and dissociation of the material, provides the most general example of the non-volatility.
In view of the foregoing, an object of the present invention is to provide a memory device with excellent heat resistance which can be used with a high degree of reliability in any environment by realizing a non-volatile memory which utilizes chemical change as state transition.
Though the non-volatile memory which utilizes chemical change as state transition provides highly reliable non-volatility, it is usually difficult to controllably enhance state transition (bonding and dissociation of material). To avoid this difficulty, the present inventors have perceived a gas mixture which can react forward and backward to be a data carrier, and a micro vacuum tube to be used as a data storage means.